Acids & BasesAcids & Bases

pH Balance?pH Balance?

Video: Elements of Chemistry -Video: Elements of Chemistry -Acids, Bases & SaltsAcids, Bases & Salts

Household Acids & Bases LabHousehold Acids & Bases LabSolutionSolution Blue litmusBlue litmus Red litmusRed litmus Universal Universal

IndicatorIndicatorpHpH

VinegarVinegar

AmmoniaAmmonia Put drop Put drop onto plate.onto plate.

Unplug pH Unplug pH probe probe

Lemon juiceLemon juice Add drop of Add drop of indicator.indicator.

When done.When done.

Soft drinkSoft drink Record.Record.

Drain Drain cleanercleaner

Rinse out Rinse out plate at endplate at end

DetergentDetergent of period of period pleaseplease

Baking sodaBaking soda

Antacid Antacid (MoM)(MoM)

Mentos & PopMentos & Pop

http://http://www.stevespanglerscience.com/www.stevespanglerscience.com/experiment/00000109experiment/00000109

Properties of Acids vs BasesProperties of Acids vs Bases

Acids:Acids:

Taste Sour – vinegar!Taste Sour – vinegar!

Feel like water but sting Feel like water but sting cuts.cuts.

Turn litmus red.Turn litmus red.

React with active metals React with active metals to form explosive Hto form explosive H22 gas.gas.

Act as electrolytes to Act as electrolytes to conduct electricity.conduct electricity.

Neutralize bases!Neutralize bases!

Bases:Bases:

Taste bitter – soap!Taste bitter – soap!

Feel slippery.Feel slippery.

Turn litmus blue.Turn litmus blue.

Don’t react with most Don’t react with most metals.metals.

Act as electrolytes to Act as electrolytes to conduct electricity.conduct electricity.

Neutralize acids!Neutralize acids!

Arrhenius Acids & BasesArrhenius Acids & Bases

Acids:Acids: Release HRelease H++ ions by ions by

dissociation. dissociation. Example: HClExample: HCl Combine HCombine H++ with with

any negative ion any negative ion on your ion chart on your ion chart to form an acid.to form an acid.

Examples: ???Examples: ???

Bases:Bases: Release OHRelease OH-- ions ions

by dissociation.by dissociation. Example: NaOHExample: NaOH Combine OHCombine OH-- with with

any metal on the any metal on the periodic table to periodic table to form a base.form a base.

Examples: ???Examples: ???

Arrhenius ExplanationsArrhenius Explanations

H+ provides the sour taste & stings.H+ provides the sour taste & stings. OH- the bitter taste & is slippery.OH- the bitter taste & is slippery. Dissociation of both acids & bases Dissociation of both acids & bases

produces dissolved ions which act as produces dissolved ions which act as electrolytes.electrolytes.

Neutralization occurs when H+ & OH- Neutralization occurs when H+ & OH- combine to form H2O. The left overs combine to form H2O. The left overs produce a salt like NaCl.produce a salt like NaCl.

Bronsted-Lowry Acids & BasesBronsted-Lowry Acids & Bases

Acids:Acids: Donate H+ ions.Donate H+ ions. Example: Acetic Example: Acetic

acid & amino acids.acid & amino acids. H+ ions are H+ ions are

protons.protons. Acids may be Acids may be

monoprotic, diprotic monoprotic, diprotic or triprotic.or triprotic.

Examples: Examples:

Bases: Bases: Accept H+ ions.Accept H+ ions. Example: Example:

Ammonia, NHAmmonia, NH33

All inclusive All inclusive including bases including bases ignored by ignored by Arrhenius.Arrhenius.

Conjugate Acids & BasesConjugate Acids & Bases

Acids release H+ & bases accept H+.Acids release H+ & bases accept H+.

Once an acid releases its H+ it Once an acid releases its H+ it becomes a base that can accept H+ becomes a base that can accept H+ & vice versa.& vice versa.

Examples:Examples:

HH22COCO33 vs HCO vs HCO33-1-1

NHNH33 vs NH vs NH44+1+1

HH22O vs HO vs H33OO+1+1

Hydronium IonHydronium Ion

Water is amphoteric – it can act as both an Water is amphoteric – it can act as both an acid & a base.acid & a base.

When water acts as a base, it forms the When water acts as a base, it forms the hydronium ion.hydronium ion.

HH22O + HO + H++ H H33OO++

H+ ions always bind to something.H+ ions always bind to something. When water acts as an acid it forms OH-.When water acts as an acid it forms OH-. HH220 0 OH OH-- + H + H++

The fraction of water that normally The fraction of water that normally dissociates is 10dissociates is 10-7-7 M. A very small fraction! M. A very small fraction! 1/10million!1/10million!

pH Measures the H+ ConcentrationpH Measures the H+ Concentration

pH uses logs which are just powers of 10.pH uses logs which are just powers of 10. pH measures the electric “potential” of pH measures the electric “potential” of

H+ ions in a solution.H+ ions in a solution. pH is calculated as the negative “power” pH is calculated as the negative “power”

of 10 of the H+ ion concentration.of 10 of the H+ ion concentration. The equation for pH is pH = -log[H+]The equation for pH is pH = -log[H+] [brackets] mean concentration in [brackets] mean concentration in

Molarity.Molarity. pH 7 is neutral, above 7 is basic & below pH 7 is neutral, above 7 is basic & below

7 is acidic.7 is acidic.

Simple pH CalculationsSimple pH Calculations

AcidAcid3.33.31010-3.3-3.3.00047.00047

BaseBase12121010-12-12.000000000001.000000000001

BaseBase991010-9-9.000000001.000000001

neutralneutral771010-7-7.0000001.0000001

AcidAcid551010-5-5.00001.00001

AcidAcid331010-3-3.001.001

Acid or Acid or Base?Base?

pHpHPower of Power of 1010

HH++ Molarity Molarity

pH Quiz – Determine the pH of:pH Quiz – Determine the pH of:

1.1. A 4.63 x 10A 4.63 x 10-8-8M solution of HNO3.M solution of HNO3.

2.2. A 250L solution containing 4.3mol A 250L solution containing 4.3mol of HCl.of HCl.

3.3. A 750.0ml solution containing A 750.0ml solution containing 0.0046g of HBr.0.0046g of HBr.

4.4. A 8.9L solution of 0.65mol of A 8.9L solution of 0.65mol of H2SO4.H2SO4.

Titrations 5/13/08Titrations 5/13/08

SimulationsSimulations http://www.sciencegeek.net/Shockwave/Tithttp://www.sciencegeek.net/Shockwave/Tit

ration.htmration.htm Lesson:Lesson: Simulation DemoSimulation Demo NotesNotes Practice ProblemsPractice Problems Work ProblemsWork Problems Asmt: Simulation Problems A-E find [H+] Asmt: Simulation Problems A-E find [H+]

in Min M

TitrationsTitrations Titrations measure the concentration of Titrations measure the concentration of

solutions by finding out the amount of a known solutions by finding out the amount of a known solution needed to neutralize an unknown solution needed to neutralize an unknown solution.solution.

Neutralization occurs when Mol H+ = Mol of Neutralization occurs when Mol H+ = Mol of OH-OH-

M = mol/L M = mol/L mol = L x M mol = L x M mol = M x Vmol = M x V MMaaVVaa = M = MbbVVb b (a is for acid, b is for base)(a is for acid, b is for base) Some acids are diprotic or triprotic, some Some acids are diprotic or triprotic, some

bases are multi-hydroxy.bases are multi-hydroxy. AMAMaaVVaa = BM = BMbbVVb b

(A is for # of H+, B is for # of OH-)(A is for # of H+, B is for # of OH-)

Friday 6-11-04Friday 6-11-04

Prep: Prep: 1.1. Litmus papers, droppers fill up bottles.Litmus papers, droppers fill up bottles.2.2. Graduation RehearsalGraduation RehearsalClassClass1.1. End of Year ScheduleEnd of Year Schedule2.2. Vocabulary AssignmentVocabulary Assignment3.3. Lab – pH of Household SubstancesLab – pH of Household Substances

Predictions Predictions Handling the pH probe & storage bottleHandling the pH probe & storage bottle Litmus tests & universal indicatorLitmus tests & universal indicator

Acid – Base VocabularyAcid – Base Vocabulary

AcidAcidBaseBaseIndicatorIndicatorNeutralizationNeutralizationHydronium ionHydronium ionAmphotericAmphotericConjugate acidConjugate acidConjugate baseConjugate baseDissociationDissociation

pH pH BufferBufferTitrationTitrationEquivalence pointEquivalence point

pH of Household SubstancespH of Household SubstancesSamplSamplee

PredicPredict pHt pH

Red Red LitmusLitmus

Blue Blue LitmusLitmus

Univ. Univ. Indic-Indic-atorator

pHpH

ActualActual

pH of Household SubstancespH of Household Substances1.1. Make the following data table in your notebook. Make the following data table in your notebook. 2.2. Rank & predict pH of samples to be used: soda pop, Rank & predict pH of samples to be used: soda pop,

drain cleaner, vinegar, ammonia, lemon juice, drain cleaner, vinegar, ammonia, lemon juice, detergent, baking sodadetergent, baking soda

3.3. ½ fill a well in the plate for each sample.½ fill a well in the plate for each sample.4.4. Test with red litmus, blue litmus & then add 1 drop of Test with red litmus, blue litmus & then add 1 drop of

universal indicator to observe the color. Dispose universal indicator to observe the color. Dispose down sink.down sink.

5.5. pH Probe:pH Probe: Cap stays on probe. Place storage bottle by faucet.Cap stays on probe. Place storage bottle by faucet. Rinse probe with distilled water before each test. Rinse probe with distilled water before each test. Place probe in each sample bottle. Place probe in each sample bottle. Swirl sample around probe for 30 seconds.Swirl sample around probe for 30 seconds. Record pH from top right corner of calculator.Record pH from top right corner of calculator. Recap all bottles when not in use.Recap all bottles when not in use.

Monday 6/14/04Monday 6/14/04Prep:Prep:1. Get copies of tracking hurricanes for 14 1. Get copies of tracking hurricanes for 14

juniors. juniors. 2. Update Chemistry Aces2. Update Chemistry Aces3. Prepare for Rainbow Titrations Lab3. Prepare for Rainbow Titrations LabClass:Class:Recollect Final Answers from 5Recollect Final Answers from 5thth Period Period1.1. Schedule of WeekSchedule of Week2.2. Due: Acids & Bases VocabularyDue: Acids & Bases Vocabulary3.3. Review Household Acids & BasesReview Household Acids & Bases4.4. Notes: Acids & Bases (10 points)Notes: Acids & Bases (10 points)

1.1. PropertiesProperties2.2. DefinitionsDefinitions3.3. pHpH

Tuesday 6/15/04Tuesday 6/15/04

Prep:Prep:

1.1. Print 40 copies of the Final KeysPrint 40 copies of the Final Keys

2.2. Distribute supplies for Rainbow Distribute supplies for Rainbow Titration Lab (test burets & stopcocks)Titration Lab (test burets & stopcocks)

Class:Class:

1.1. Pass out Final Exams – check keys & Pass out Final Exams – check keys & addition of scores. RECOLLECT!addition of scores. RECOLLECT!

2.2. Rainbow Titration LabRainbow Titration Lab

Rainbow Titration LabRainbow Titration LabGoal: Determine all the distinct colors and their Goal: Determine all the distinct colors and their

corresponding pH ranges for Universal Indicator.corresponding pH ranges for Universal Indicator.Procedures for Each Trial:Procedures for Each Trial:1.1. Add 25 ml of 0.1M HCl to a 100ml beaker. Add Add 25 ml of 0.1M HCl to a 100ml beaker. Add

6 drops of Universal. (Person A)6 drops of Universal. (Person A)2.2. Close the stopcock on the buret. Add 50 ml of Close the stopcock on the buret. Add 50 ml of

0.1M NaOH to the buret. (Person B)0.1M NaOH to the buret. (Person B)3.3. Place the magnetic stir bar in the beaker of Place the magnetic stir bar in the beaker of

liquid & turn it on a medium spin. (Person C)liquid & turn it on a medium spin. (Person C)4.4. Set up the pH probe to monitor the liquid in the Set up the pH probe to monitor the liquid in the

beaker. (Person D)beaker. (Person D)5.5. Open the stopcock to SLOWLY drip base from Open the stopcock to SLOWLY drip base from

the buret to the acid in the beaker. (Person B)the buret to the acid in the beaker. (Person B)6.6. Record your observations of colors & pH. Record your observations of colors & pH.

(Everyone)(Everyone)7.7. Check your results with the instructor. Check your results with the instructor.

(Everyone)(Everyone)

Monday 6/20/05Monday 6/20/05

DMA: Copy 3 titration problemsDMA: Copy 3 titration problems

1.1. Finish pH notesFinish pH notes

2.2. Titration NotesTitration Notes

3.3. Demo: Titrate ?M H2SO4 w/ 2M Demo: Titrate ?M H2SO4 w/ 2M NaOHNaOH

Asmt: 3 titration problemsAsmt: 3 titration problems

Titration ProblemsTitration Problems

1.1. If 20.00ml of acidic drain cleaner is If 20.00ml of acidic drain cleaner is titrated completely by 18.02ml of titrated completely by 18.02ml of 0.100M NaOH, what is the acid’s 0.100M NaOH, what is the acid’s concentration?concentration?

2.2. A 25.1ml volume of KOH is titrated A 25.1ml volume of KOH is titrated with 43.2ml of 0.150M Hwith 43.2ml of 0.150M H22SOSO44. What . What is the molarity of the KOH?is the molarity of the KOH?

3.3. A volume of 34.0ml of 0.100M HA volume of 34.0ml of 0.100M H33POPO44 neutralizes 25.0ml of Ba(OH)neutralizes 25.0ml of Ba(OH)22. What . What is the concentration of the barium is the concentration of the barium hydroxide?hydroxide?

Tuesday 6/21/05Tuesday 6/21/05

Prep:Prep:1.1. Get copies of Acid-Base Mini-ExamGet copies of Acid-Base Mini-Exam2.2. Make fine cards! Make fine cards! Class:Class:1.1. Pass out AP Bio stuff.Pass out AP Bio stuff.2.2. Review a titration problem.Review a titration problem.3.3. Acid-Base Mini-ExamAcid-Base Mini-Exam4.4. Pass back finals / fine cards / check basmati/ sign Pass back finals / fine cards / check basmati/ sign

annuals.annuals.Plan:Plan:1.1. Fill out fine cards!Fill out fine cards!2.2. Call Mary Anne about visiting Bob.Call Mary Anne about visiting Bob.After School: After School: 1.1. Help students. Help students. 2.2. Clean up lab. Clean up lab.

Vinegar Titration LabVinegar Titration Lab

Add 10.0 ml of vinegar to the beaker. Add Add 10.0 ml of vinegar to the beaker. Add 4 drops of indicator B, phenolpthalein.4 drops of indicator B, phenolpthalein.

Fill the buret with 1.00M NaOH. Record Fill the buret with 1.00M NaOH. Record the starting volume.the starting volume.

Titrate until the mixture turns pink & stays Titrate until the mixture turns pink & stays pink. Use the minimum of drops.pink. Use the minimum of drops.

Measure the final volume and determine Measure the final volume and determine the change in volume of the base.the change in volume of the base.

Use AMaVa = BMbVb to determine the Use AMaVa = BMbVb to determine the molarity of the vinegar, HC2H3O2.molarity of the vinegar, HC2H3O2.

Antacid Titration LabAntacid Titration LabGoal: Determine which Antacid will neutralize the Goal: Determine which Antacid will neutralize the

greatest amount of stomach acid – Rolaids, greatest amount of stomach acid – Rolaids, Tums, or MaaloxTums, or Maalox

1.1. Pulverize a sample tablet with the mortar & Pulverize a sample tablet with the mortar & pestle.pestle.

2.2. Dissolve sample with 25ml of distilled water & Dissolve sample with 25ml of distilled water & transfer the solution to a 100ml beaker.transfer the solution to a 100ml beaker.

3.3. Add 4 drops of bromothymol blue? and the stir Add 4 drops of bromothymol blue? and the stir bar.bar.

4.4. Add 0.1M HCl to the buret. Record precisely the Add 0.1M HCl to the buret. Record precisely the starting volume in the buret.starting volume in the buret.

5.5. Use the Use the minimumminimum amount of 1.0M HCl needed to amount of 1.0M HCl needed to turn the solution yellow? and stay clear.turn the solution yellow? and stay clear.

6.6. Record the final volume of the buret. Find the Record the final volume of the buret. Find the change in volume.change in volume.

7.7. Repeat for each sample. Repeat for each sample.

Friday 6/18/04Friday 6/18/04Prep: Prep: 1.1. Set up titration demo.Set up titration demo.2.2. Get extra fine cards.Get extra fine cards.Class:Class:1.1. Return book or receive fine card tied to Return book or receive fine card tied to

grade report.grade report.2.2. Check Basmati – bring personal issues to Check Basmati – bring personal issues to

me after mini-exam.me after mini-exam.3.3. Begin titration demo (5ml vs 50ml)Begin titration demo (5ml vs 50ml)4.4. Review for mini-exam, no 3x5 cardReview for mini-exam, no 3x5 card5.5. Acids & Bases Mini-Exam – Check notes???Acids & Bases Mini-Exam – Check notes???XC Asmt: 5 points if you bring treats for XC Asmt: 5 points if you bring treats for

everyone for Monday’s Annual Signing everyone for Monday’s Annual Signing PartyParty

Conjugate Acids & BasesConjugate Acids & Bases

Any acid that can release H+ can re-accept Any acid that can release H+ can re-accept and bind it to varying degrees.and bind it to varying degrees.

Strong acids like HCl release essentially all Strong acids like HCl release essentially all H+ ions. HCl H+ ions. HCl H H++ + Cl + Cl--

Weak acids like in vinegar release a small Weak acids like in vinegar release a small percentage of H+ ions. Most remain bound.percentage of H+ ions. Most remain bound.

HCHC22HH33OO22 H H++ + C + C22HH33OO22--

Salts contain positive & negative ions.Salts contain positive & negative ions. Any negative ion has some capacity to bind Any negative ion has some capacity to bind

with H+ ions to act like a base. with H+ ions to act like a base. Examples: ???Examples: ???

Conjugates represent examples with or Conjugates represent examples with or without H+ attached. Examples: ???without H+ attached. Examples: ???

Equilibrium of Reversible ReactionsEquilibrium of Reversible Reactions

Carbonated Water:Carbonated Water:

COCO2(g)2(g) + H + H22O O (l)(l) H H22COCO3(aq)3(aq)

HH22COCO3(aq)3(aq) H H++(aq)(aq) + HCO + HCO33

--(aq)(aq)

Le Chatelier’s Principal – When disturbed Le Chatelier’s Principal – When disturbed a reaction will adjust to minimize the a reaction will adjust to minimize the disturbance. (Teeter totter analogy)disturbance. (Teeter totter analogy)

Carbonate pop by adding COCarbonate pop by adding CO2(g)2(g) pressure. pressure.

COCO2(g)2(g) + H + H22O O (l)(l) H H22COCO3(aq)3(aq)

Pop goes flat when container is opened!Pop goes flat when container is opened!

COCO2(g)2(g) + H + H22O O (l)(l) H H22COCO3(aq)3(aq)

Equilibrium RatiosEquilibrium Ratios

xAxA(aq)(aq) + + yByB(aq)(aq) zCzC(aq)(aq) Equilibrium Ratio (K) = products/reactantsEquilibrium Ratio (K) = products/reactants

KKeqeq = [C] = [C]z z / [A]/ [A]xx[B][B]yy Coefficients = exponents!Coefficients = exponents!

Carbonated Water Equilibrium Ratio?Carbonated Water Equilibrium Ratio?

Each reaction has a different equilibrium Each reaction has a different equilibrium ratio value.ratio value.

Large ratios favor the _________, while small Large ratios favor the _________, while small ratios favor the _________.ratios favor the _________.